This site gives an explanation, a definition of and an example for tests of significance. Topics include null and alternative hypotheses for population mean, one-sided and two-sided z and t tests, levels of significance, and matched pairs analysis.

This site gives an explanation, a definition and an example of inference for categorical data. Topics include confidence intervals and significance tests for a single proportion, as well as comparison of two proportions.

This site provides the description and instructions for as well as the link to The Self-Avoiding Random Walk applet. In the SAW applet, random walks start on a square lattice and then are discarded as soon as they self-intersect. If a random walk survives after N steps, we compute the square of the distance from the origin, sum it up, and divide by the number of survivals. This variable is plotted on the vertical axis of the graph, which is plotted to the right of the field where random walks travel.